GB2244405A - Airborne radar for speed measurement - Google Patents

Airborne radar for speed measurement Download PDF

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Publication number
GB2244405A
GB2244405A GB9011375A GB9011375A GB2244405A GB 2244405 A GB2244405 A GB 2244405A GB 9011375 A GB9011375 A GB 9011375A GB 9011375 A GB9011375 A GB 9011375A GB 2244405 A GB2244405 A GB 2244405A
Authority
GB
United Kingdom
Prior art keywords
velocity
platform
relative
speed
feature
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
GB9011375A
Other versions
GB9011375D0 (en
Inventor
Stephen Richard Lilley
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Roke Manor Research Ltd
Plessey Co Ltd
Original Assignee
Roke Manor Research Ltd
Plessey Co Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Roke Manor Research Ltd, Plessey Co Ltd filed Critical Roke Manor Research Ltd
Priority to GB9011375A priority Critical patent/GB2244405A/en
Publication of GB9011375D0 publication Critical patent/GB9011375D0/en
Publication of GB2244405A publication Critical patent/GB2244405A/en
Withdrawn legal-status Critical Current

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Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01C—MEASURING DISTANCES, LEVELS OR BEARINGS; SURVEYING; NAVIGATION; GYROSCOPIC INSTRUMENTS; PHOTOGRAMMETRY OR VIDEOGRAMMETRY
    • G01C25/00—Manufacturing, calibrating, cleaning, or repairing instruments or devices referred to in the other groups of this subclass
    • G01C25/005—Manufacturing, calibrating, cleaning, or repairing instruments or devices referred to in the other groups of this subclass initial alignment, calibration or starting-up of inertial devices
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S13/00—Systems using the reflection or reradiation of radio waves, e.g. radar systems; Analogous systems using reflection or reradiation of waves whose nature or wavelength is irrelevant or unspecified
    • G01S13/02—Systems using reflection of radio waves, e.g. primary radar systems; Analogous systems
    • G01S13/50—Systems of measurement based on relative movement of target
    • G01S13/58—Velocity or trajectory determination systems; Sense-of-movement determination systems
    • G01S13/60—Velocity or trajectory determination systems; Sense-of-movement determination systems wherein the transmitter and receiver are mounted on the moving object, e.g. for determining ground speed, drift angle, ground track

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  • Engineering & Computer Science (AREA)
  • Radar, Positioning & Navigation (AREA)
  • Remote Sensing (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Manufacturing & Machinery (AREA)
  • Radar Systems Or Details Thereof (AREA)

Abstract

The system employs a monopulse radar providing sum and difference doppler signals from a stationary feature under the radar. The bearing of the feature and the velocity of the system relative to the feature are determined and the absolute velocity or speed is calculated from those values. The velocity measurement may be used to correct drift in an inertial navigation system. <IMAGE>

Description

AIRBORNE RADAR FOR SPEED MEASUREMENT FIELD OF THE INVENTION This invention relates to an airborne radar for speed measurement, having particular though not exclusive application to the correction of inertial navigation systems.
BACKGROUND ART Airborne platforms such as aircraft, helicopters etc are commonly fitted with inertial navigation systems so that the platform may navigate itself autonomously without reference to external navigational aids such as the global positioning system. A problem arises in that inertial navigational systems commonly are subject to drift, and a large error will eventually occur in the estimate by the navigational system of the vehicle velocity or speed.
This can lead to serious navigational errors.
SUMMARY OF THE INVENTION It is an object of the invention to provide a radar system for an airborne platform which may be employed to compute the velocity or speed of the platform and if necessary apply this computation for correction of an inertial navigational system.
The present invention provides a radar system for an airborne platform for estimating speed or velocity of the platform, the system including a monopulse system for providing sum and difference beams in a predetermined direction relative to the aircraft, the monopulse system including receiver means for detecting the sum and difference beams when reflected from a stationary feature of the terrain under the platform, means for computing from the detected reflected pulses the bearing of the stationary feature relative to the heading of the aircraft, and means for estimating the doppler frequency shift in the reflected pulses in order to compute the relative velocity of the platform relative to the stationary feature, and means for computing from said relative velocity and said angle the absolute velocity or speed of the platform.
Thus in accordance with the invention, a monopulse technique is employed to derive the bearing of a stationary feature relative to the heading of the platform (both in azimuth and elevation). Doppler filtering derives the relative speeds of the platform relative to the stationary objects. As will be seen below, this enables the absolute speed or velocity of the platform to be calculated.
An advantage of the invention arises in that a practically instantaneous determination of absolute velocity is available, whereas other techniques which might be employed which rely upon determination of the time of flight between two objects in the flight path of the platform necessarily take a long time to compute.
BRIEF DESCRIPTION OF THE DRAWINGS A preferred embodiment of the invention will now be described with reference to the accompanying drawings wherein:- Figure 1 is a schematic illustrating the means by which the present invention computes absolute velocity or speed; and, Figure 2 illustrates a preferred embodiment of the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENT Figure 1 describes the principle by which the speed of the platform is estimated, from measurements of relative velocity (Doppler frequency) and angle off velocity vector.
Thus if relative velocity = VR, this is a function of velocity vector magnitude (V) and angles off velocity vector (0, ) (azimuth and elevation).
Then VR = V cos (0) cos ( ).
For any VR by measuring 0 and inverting this equation gives an estimate of V.
The equation states that from a direction relative to the velocity vector given by the two angles, the relative velocity of signals (returned from stationary objects) will be the product of the velocity vector magnitude and the cosines of the two angles.
Thus by setting up a Doppler filter to only pass signals of a particular relative velocity, and then estimating the angles of arrival of those signals passed, the equation can be inverted to provide an estimate of speed.
Figure 2 describes this method in more detail, showing three separate receive channels leaving the antenna. One of these is the conventional antenna beam, or sum beam, whilst the other two are the difference beams by which angle is estimated by comparison against the signal in the sum beam. This technique is referred to as monopulse.
The three channels are passed to sets of identical Doppler filters. The doppler filters and other signal processing elements (not shown) enable an array of time (range)/Doppler shift cells to be computed. Each time/Doppler cell out of the filter bank will have a sum signal, an azimuth difference beam signal, and an elevation difference beam signal. This is converted by monopulse processing to a statement of azimuth and elevation for each cell, which in turn is converted to a velocity estimate for each cell, as described by Figure 1. The estimates from all range/Doppler cells are then integrated in a weighted average to produce a best estimate of velocity vector magnitude (speed).

Claims (1)

  1. CLAIMS:
    1. A radar system for an airborne platform for estimating speed or velocity of the platform, the system including a monopulse system for providing sum and difference beams in a predetermined direction relative to the aircraft, the monopulse system including receiver means for detecting the sum and difference beams when reflected from a stationary feature of the terrain under the platform, means for computing from the detected reflected pulses the bearing of the stationary feature relative to the heading of the aircraft, and means for estimating the doppler frequency shift in the reflected pulses in order to compute the relative velocity of the platform relative to the stationary feature, and means for computing from said relative velocity and said angle the absolute velocity or speed of the platform.
GB9011375A 1990-05-22 1990-05-22 Airborne radar for speed measurement Withdrawn GB2244405A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
GB9011375A GB2244405A (en) 1990-05-22 1990-05-22 Airborne radar for speed measurement

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB9011375A GB2244405A (en) 1990-05-22 1990-05-22 Airborne radar for speed measurement

Publications (2)

Publication Number Publication Date
GB9011375D0 GB9011375D0 (en) 1990-11-21
GB2244405A true GB2244405A (en) 1991-11-27

Family

ID=10676336

Family Applications (1)

Application Number Title Priority Date Filing Date
GB9011375A Withdrawn GB2244405A (en) 1990-05-22 1990-05-22 Airborne radar for speed measurement

Country Status (1)

Country Link
GB (1) GB2244405A (en)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2750214A1 (en) * 1996-06-21 1997-12-26 Thomson Csf METHOD OF CALIBRATING POSITIONING ERRORS OF A RADAR AND THE FLOOR DRIFT OF AN INERTIAL PLANT EMBEDDED ABOARD AN AIRCRAFT
DE102007020264A1 (en) * 2007-04-30 2008-11-20 Tyco Electronics Amp Gmbh Method and measuring device for determining a relative speed
RU2741400C2 (en) * 2019-06-19 2021-01-25 Закрытое акционерное общество "Научно-исследовательский центр "Резонанс" (ЗАО "НИЦ "Резонанс") Method and device for determining the track speed of a nonmaneuvering object based on the range products selection on the radial velocity
DE102010015723B4 (en) 2010-04-21 2023-10-12 Volkswagen Ag Method and device for detecting movement of a road vehicle

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1583406A (en) * 1976-08-02 1981-01-28 Raytheon Co Doppler navigation radar apparatus

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1583406A (en) * 1976-08-02 1981-01-28 Raytheon Co Doppler navigation radar apparatus

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2750214A1 (en) * 1996-06-21 1997-12-26 Thomson Csf METHOD OF CALIBRATING POSITIONING ERRORS OF A RADAR AND THE FLOOR DRIFT OF AN INERTIAL PLANT EMBEDDED ABOARD AN AIRCRAFT
EP0814347A1 (en) * 1996-06-21 1997-12-29 Thomson Csf Method for calibrating the positioning error of a radar and the ground velocity drift of an inertial system installed on board of an aircraft
US5883593A (en) * 1996-06-21 1999-03-16 Thomson-Csf Method for the calibration of the positioning errors of a radar and the drift in ground speed of an inertial unit on board an aircraft
DE102007020264A1 (en) * 2007-04-30 2008-11-20 Tyco Electronics Amp Gmbh Method and measuring device for determining a relative speed
US7598904B2 (en) 2007-04-30 2009-10-06 Autoliv Asp, Inc. Method and measuring device for determining a relative velocity
DE102010015723B4 (en) 2010-04-21 2023-10-12 Volkswagen Ag Method and device for detecting movement of a road vehicle
RU2741400C2 (en) * 2019-06-19 2021-01-25 Закрытое акционерное общество "Научно-исследовательский центр "Резонанс" (ЗАО "НИЦ "Резонанс") Method and device for determining the track speed of a nonmaneuvering object based on the range products selection on the radial velocity

Also Published As

Publication number Publication date
GB9011375D0 (en) 1990-11-21

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Legal Events

Date Code Title Description
730A Proceeding under section 30 patents act 1977
WAP Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1)